The present invention relates to the field of angioplasty. In particular, the present invention is a guide catheter having three principal segments, with each segment having a different degree of flexibility.
Angioplasty has gained wide acceptance in recent years as an efficient and effective method for treating various types of vascular diseases. In particular, angioplasty is widely used for opening stenoses in the coronary arteries, although it is also used for treatment of stenoses in other parts of the vascular system.
The most widely used form of angioplasty makes use of a guide catheter positioned within the vascular system of a patient. The distal end of the guide catheter is inserted into the femoral artery located in the groin of the patient and pushed distally up through the vascular system until the distal end of the guide catheter is located in the ostium of the coronary artery. The distal end of the guide catheter is normally curved so that the distal tip of the guide catheter is more easily directed to the coronary ostium of the patient. The distal tip of the guide catheter is typically formed from relatively soft, flexible material to avoid trauma to arterial vessels, and allow flexing of the distal tip to aid the guide catheter in traversing desired arterial branches. That portion of the guide catheter proximal to the distal tip is typically stiffer to enhance torqueability and pushability which further assist the guide catheter in traversing the patient's vascular system. The proximal end of the guide catheter protrudes outside the patient's body to provide an entryway for subsequent insertion of additional angioplasty devices. The additional angioplasty devices include dilatation catheters such as non-over-the-wire and over-the-wire balloon catheters.
Angiographic catheters having soft, flexible distal tips and stiffer proximal segments are generally known. U.S. Pat. No. 4,385,635 to Ruiz discloses one such catheter. The catheter includes a soft tip or terminal zone, an intermediate zone and a main fully reinforced length. An exterior jacket which is relatively soft and flexible extends along the entire length of the catheter. Within the main length of the jacket is a reinforcing tube which is adhered to the inside diameter of the exterior jacket. The reinforcing tube is relatively rigid to provide torque control. In the intermediate zone, the exterior jacket is tapered so that it is enlarged in cross-section at the distal portion of the intermediate zone. The reinforcing the within the intermediate zone is tapered to provide an easy transition between the main fully reinforced length and the soft tip. The reinforcing tube tapers to zero such that the soft tip consists entirely of the exterior jacket. The intermediate zone provides decreasing stiffness between the main length and the soft tip of the angiographic catheter.
U.S. Pat. No. 5,045,072 to Castillo et al. discloses a catheter having a catheter body, a distal tip and a transition zone that connects the distal tip to the catheter body. The transition zone is free of tubular reinforcing braid, while the catheter body carries such reinforcing braid in its interior. The distal tip is heat bonded to a distal end of the transition zone which is in turn heat bonded at its other end to the catheter body. The distal tip is made of a first polyurethane formulation while the catheter body and transition zone are made of a second different polyurethane formulation. Both the catheter body and the transition zone are flexible, however, the distal tip exhibits greater flexibility and lower durometer than the rest of the catheter.